Reproduction
Sponges are monoecious, meaning they posses both sexes, but hardly ever self-fertilize due to the fact that they produce sperm and eggs at different moments. Flagellated sperm is produce when choanocytes lose their collars and flagella then undergoes meiosis. Also, other choanocytes go through meiosis to produce eggs.
During fertilization sponges release sperm and eggs from their osculum, while in ocean water planktonic larvae develop. Certain sponges go through fertilization when the sperm cells of the sponge, which are located in the mesohyl, leave the osculum to go to another sponge traveling in incurrent waters. The sperm of the parent sponge are collected with the choanocytes of the receiving sponge, the sperm then makes its way to the choanocytes vacuole. The choanocyte then lose their collar and flagellum, like in other forms of fertilization, then they become amoeboid and transport the sperm to the eggs.
During development a larva, immature stage that may undergo a dramatic change in structure before attaining the adult body form, is sometimes formed from the cleavage of a zygote, in other sponges development occurs in the mesohyl. The larva then leaves the sponge and roams the ocean, the larvae eventually (usually no more than two days) settles to substrate and starts to develop. The image below shows the development of two different types of larva, Parenchymula and Amphiblastula.
During fertilization sponges release sperm and eggs from their osculum, while in ocean water planktonic larvae develop. Certain sponges go through fertilization when the sperm cells of the sponge, which are located in the mesohyl, leave the osculum to go to another sponge traveling in incurrent waters. The sperm of the parent sponge are collected with the choanocytes of the receiving sponge, the sperm then makes its way to the choanocytes vacuole. The choanocyte then lose their collar and flagellum, like in other forms of fertilization, then they become amoeboid and transport the sperm to the eggs.
During development a larva, immature stage that may undergo a dramatic change in structure before attaining the adult body form, is sometimes formed from the cleavage of a zygote, in other sponges development occurs in the mesohyl. The larva then leaves the sponge and roams the ocean, the larvae eventually (usually no more than two days) settles to substrate and starts to develop. The image below shows the development of two different types of larva, Parenchymula and Amphiblastula.
Gemmules, resistant capsules with masses of amoeboid cells, are formed when certain sponges reproduce asexually. Gemmules are released when a sponge dies, gemmules are resistant to harsh conditions. During calm conditions, usually during spring, gemmules release amoeboid cells from their micropyle, a tiny opening in the gemmule. The released amoeboid cells then create a new sponge.